I have heard this quote a while ago and it still remains true for me today:

Missions is not the ultimate goal of the church. Worship is. Missions exists because worship doesn’t. Worship is ultimate, not missions, because God is ultimate, not man. When this age is over, and the countless millions of the redeemed fall on their faces before the throne of God, missions will be no more. It is a temporary necessity. But worship abides forever.

John Piper in his book Let the Nations Be Glad!

I think John Piper is dead on in putting our efforts and ministries into the right perspective. The glory of Jesus Christ far outweighs our missional efforts. We go out because Jesus is worthy of worship.